JP2012069173A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a writing characteristic and a reading characteristic by making a concentration distribution in a vertical direction of ions to be injected to a magnetic recording layer of a perpendicular magnetic recording medium a suitable concentration distribution corresponding to a layer to which the ions are injected.SOLUTION: A method for manufacturing a perpendicular magnetic recording medium 100 includes: a magnetic recording layer film formation step for film-forming a magnetic recording layer 122 on a disk substrate 110; a resist layer film formation step for film-forming a resist layer 130 on the magnetic recording layer; a patterning step for forming a predetermined pattern having concave and convex parts by changing partially the thickness of the resist layer by processing the resist layer; and an ion injection step for injecting ions into a plurality of layers including the magnetic recording layer with the resist layer placed therebetween. In the ion injection step, a layer to which the ions are injected is determined by adjusting an energy amount for injecting the ions, and the total amount of the ions to be injected to each layer is determined by adjusting time for holding the energy amount.

Description

  The present invention relates to a method for manufacturing a magnetic recording medium mounted on an HDD (hard disk drive) or the like, and a magnetic recording medium.

  Various information recording techniques have been developed with the recent increase in information processing capacity. In particular, the surface recording density of HDDs using magnetic recording technology continues to increase at an annual rate of about 100%. Recently, an information recording capacity exceeding 200 GB is required for a 2.5 inch diameter magnetic disk used for HDDs and the like, and in order to meet such a demand, per square inch. It is required to realize an information recording density exceeding 400 GB.

  In recent years, a perpendicular magnetic recording type magnetic disk (perpendicular magnetic recording disk) has been proposed in order to achieve a high recording density in a magnetic disk used for an HDD or the like. In the conventional in-plane magnetic recording method, the easy axis of magnetization of the magnetic recording layer is aligned in the plane direction of the substrate surface, but in the perpendicular magnetic recording method, the easy magnetization axis is adjusted to be aligned in the direction perpendicular to the substrate surface. ing. The perpendicular magnetic recording method is more suitable for increasing the recording density because the thermal fluctuation phenomenon can be more suppressed during high-density recording than the in-plane recording method.

  In addition, as a technology that improves recording density and thermal fluctuation resistance, discrete track media and other patterns that prevent interference between adjacent recording tracks by patterning non-magnetic tracks in parallel between recording magnetic tracks can be used. A magnetic recording medium called a bit pattern medium that is artificially regularly arranged has been proposed.

  In the patterned media such as the discrete track media and the bit pattern media described above, after a magnetic recording layer is formed on a nonmagnetic substrate, ions are partially implanted, and the portion of the magnetic recording layer into which ions are implanted is nonmagnetic. By making the magnetic recording layer of such a part into a non-recording part by making it into a non-recording part or making it amorphous, the magnetic recording part magnetically separated by the non-recording part makes the magnetic recording part and non-recording part magnetic After forming a magnetic recording layer on a non-magnetic substrate, a technology for forming a pattern, and then forming irregularities by partially milling the magnetic recording layer to physically separate the magnetic recording layer, and the magnetic recording layer A technique for forming a pattern has been proposed.

  Specifically, first, a resist is formed on the magnetic recording layer, and a stamper on which a desired uneven pattern is formed is imprinted to transfer the uneven pattern to the resist, or a photoresist is applied on the magnetic recording layer. A desired concavo-convex pattern is formed on a photoresist by photolithography. Then, ions are implanted into the magnetic recording layer through the formed recess, or the magnetic recording layer exposed on the surface of the recess is milled by etching to separate the magnetic recording layer.

  In the above-described patterned media, when irregularities are physically formed on the magnetic recording layer by milling, the resist is removed, and the concave portions are filled with a nonmagnetic substance and then smoothed. On the other hand, when the pattern is formed by ion implantation, smoothing is achieved only by removing the resist. Therefore, in a method for producing a patterned medium, patterning by ion implantation with few steps and high smoothness on the surface of a substrate has attracted attention (for example, Patent Document 1).

JP 2008-77788 A

  In the patterning of the magnetic recording layer by ion implantation described in Patent Document 1 described above, the guard band region (non-recording portion) that magnetically separates the magnetic region (magnetic recording portion) of the magnetic recording layer is desired. However, the ion concentration distribution in the vertical direction (depth direction) is not uniform. It is considered that the ion concentration is highest at a certain depth in the guard band region, and that the ion concentration gradually decreases as the distance from the depth increases in the vertical direction.

  If such a bias occurs in the ion concentration distribution in the vertical direction, although the SNR (Signal to Noise Ratio) is good, it becomes difficult to write data to the magnetic region (magnetic recording part), and as a result, the read characteristics are also improved. Deteriorate.

  In view of such a problem, the present invention provides a good concentration distribution in the vertical direction of ions to be implanted into the magnetic recording layer of the perpendicular magnetic recording medium by making the concentration distribution appropriate for the layer into which ions are implanted. It is an object of the present invention to provide a method of manufacturing a magnetic recording medium and a magnetic recording medium capable of improving the write characteristics and read characteristics (read / write characteristics) to a magnetic recording portion while maintaining the SNR.

  In order to solve the above problems, a typical configuration of a method for manufacturing a magnetic recording medium according to the present invention includes a magnetic recording layer forming step for forming a magnetic recording layer on a substrate, and a magnetic recording layer on the magnetic recording layer. A resist layer forming step for forming a resist layer, a patterning step for forming a predetermined pattern having a concave portion and a convex portion by partially changing the thickness of the resist layer by processing the resist layer, and interposing the resist layer An ion implantation step of implanting ions into a plurality of layers including the magnetic recording layer in a state in which the ion implantation is performed, and in the ion implantation step, an ion implantation layer is determined by adjusting an amount of energy for ion implantation. The total amount of ions implanted into each layer is determined by adjusting the time for holding the energy amount.

  According to the above configuration, a desired ion implantation amount (dose amount) can be implanted into a desired layer of the magnetic recording layer. For example, the case where the magnetic recording layer includes a first magnetic recording layer and a second magnetic recording layer that is formed on the first recording layer and contains more oxide than the first magnetic recording layer, which is the main recording layer. Think. In this case, the second magnetic recording layer may have a smaller dose (energy retention time) than the first magnetic recording layer. This is because since the second magnetic recording layer contains more oxide, the granularity is narrower, and magnetic separation can be easily achieved even if a small amount of ions are implanted in a short time.

  Prior to the resist layer forming step, the method further includes a continuous layer forming step of forming a continuous layer formed of a thin film that is adjacent to the upper or lower side of the magnetic recording layer and is magnetically continuous in the plane direction. In the implantation step, ions may be implanted into the continuous layer by adjusting the amount of energy for implanting ions and the time for maintaining the amount of energy.

  According to the above configuration, by increasing or decreasing the energy amount, ions can be implanted into the continuous layer regardless of whether the continuous layer is formed above or below the magnetic recording layer. Thereby, the coercive force Hc adjusted mainly by the magnetic recording layer and the reverse domain nucleation magnetic field Hn adjusted mainly by the continuous layer can be individually adjusted. As a result, it is possible to improve the write characteristics and read characteristics to the magnetic recording portion while maintaining a good SNR.

1 selected from the group consisting of B, P, Si, F, C, In, Bi, Kr, Ar, Xe, W, As, Ge, Mo, Sn, N ₂ , and O _{2 in} the ion implantation process. Alternatively, a plurality of ions may be implanted.

  In the above ion implantation step, the energy amount for ion implantation may be 1 to 50 keV. If the amount of energy for ion implantation is less than 1 keV, the magnetic recording portion in the magnetic recording layer cannot be magnetically separated, and cannot be configured as a patterned medium. If it is 50 keV or more, demagnetization or amorphization of the magnetic recording layer is promoted too much, leading to deterioration of read / write characteristics or demagnetization up to the magnetic recording portion.

In the ion implantation step, the total amount of ions to be implanted may be 1.0 × 10 ^{15 to} 1.0 × 10 ¹⁷ atoms / cm ² .

  The magnetic recording layer may contain one or more elements selected from the group consisting of Fe, Pt, Ru, Co, Cr, and Pd.

  The magnetic recording layer may be a ferromagnetic layer having a granular structure in which a grain boundary portion made of a nonmagnetic substance is formed between crystal grains grown in a columnar shape. In particular, when the magnetic recording layer is a discrete track medium, the SNR is improved if the magnetic recording layer has a granular structure.

  When ions are implanted in the ion implantation step, the magnetic recording layer becomes a magnetic recording portion as a recording region under the convex portion of the resist layer, and a non-recording portion under the concave portion of the resist layer, The magnetic recording medium may be a bit patterned medium having magnetic recording portions scattered on the main surface.

  When ions are implanted in the ion implantation step, the magnetic recording layer becomes a magnetic recording portion as a recording region under the convex portion of the resist layer, and a non-recording portion under the concave portion of the resist layer, The magnetic recording medium may be a discrete track medium in which linearly formed magnetic recording portions and non-recording portions are alternately arranged in the radial direction. Thereby, it is possible to improve the thermal fluctuation resistance of the magnetic recording medium and to promote higher recording density.

  In the above ion implantation step, the amount of energy for ion implantation may be adjusted so as to gradually decrease from a high value to a low value, and ions may be sequentially implanted from a deep layer to a shallow layer.

  In the above ion implantation step, the amount of energy for ion implantation may be adjusted so as to gradually increase from a low value to a high value, and ions may be sequentially implanted from a shallow layer to a deeper layer.

  In order to solve the above problems, a typical configuration of a magnetic recording medium according to the present invention is characterized by being manufactured using any one of the above-described methods for manufacturing a magnetic recording medium.

  As described above, the concentration distribution in the vertical direction of ions implanted into the magnetic recording layer is set to an appropriate concentration distribution according to the layer into which ions are implanted, and the coercive force Hc and the reverse domain nucleation magnetic field Hn are individually set. By adjusting, it is possible to improve the write characteristics and read characteristics to the magnetic recording part while maintaining a good SNR.

It is a figure explaining the structure of the perpendicular magnetic recording medium concerning embodiment. It is explanatory drawing for demonstrating the magnetic track pattern formation process concerning this embodiment. It is a figure which illustrates the conditions of the ion implantation performed in a present Example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Embodiment)
An embodiment of a method for manufacturing a magnetic recording medium according to the present invention will be described. FIG. 1 is a diagram illustrating a configuration of a bit pattern type perpendicular magnetic recording medium 100 (hereinafter simply referred to as a perpendicular magnetic recording medium 100) as a magnetic recording medium according to the present embodiment. A perpendicular magnetic recording medium 100 shown in FIG. 1 includes a disk substrate 110 as a substrate, an adhesion layer 112, a first soft magnetic layer 114a, a spacer layer 114b, a second soft magnetic layer 114c, a pre-underlayer 116, and a first underlayer 118a. , A second underlayer 118b, a nonmagnetic granular layer 120, a magnetic recording layer 122, a continuous layer 124, a protective layer 126, and a lubricating layer 128. The first soft magnetic layer 114a, the spacer layer 114b, and the second soft magnetic layer 114c together constitute the soft magnetic layer 114. The first base layer 118a and the second base layer 118b together constitute the base layer 118.

  As will be described below, the perpendicular magnetic recording medium 100 shown in the present embodiment includes a plurality of types of oxides (hereinafter referred to as “composite oxides”) in the magnetic recording layer 122, thereby providing non-magnetic properties. The composite oxide is segregated at the grain boundaries.

[Substrate molding process]
As the disk substrate 110, a glass disk obtained by forming amorphous aluminosilicate glass into a disk shape by direct pressing can be used. The type, size, thickness, etc. of the glass disk are not particularly limited. Examples of the material of the glass disk include aluminosilicate glass, soda lime glass, soda aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, quartz glass, chain silicate glass, or glass ceramic such as crystallized glass. It is done. The glass disk is subjected to grinding, polishing, and chemical strengthening sequentially to obtain a smooth non-magnetic disk base 110 made of a chemically strengthened glass disk.

[Film formation process]
On the disk substrate 110 obtained by the substrate molding process described above, the adhesion layer 112, the soft magnetic layer 114, the pre-underlayer 116, the underlayer 118, the nonmagnetic granular layer 120, and the magnetic recording layer 122 (by the DC magnetron sputtering method). The magnetic recording layer forming step) and the continuous layer 124 (continuous layer forming step) can be sequentially formed, and the protective layer 126 (protective layer forming step) can be formed by a CVD method. Note that it is also preferable to use an in-line film forming method in terms of high productivity. Hereinafter, the structure of each layer and the magnetic pattern forming process including the resist layer film forming process, the patterning process, the ion implantation process, and the removing process, which are the features of this embodiment, will be described.

  The adhesion layer 112 is amorphous and is formed in contact with the disk substrate 110, and has a function of increasing the peel strength between the soft magnetic layer 114 and the disk substrate 110 formed thereon. When the disk substrate 110 is made of amorphous glass, the adhesion layer 112 is preferably an amorphous alloy film so as to correspond to the amorphous glass surface. As the adhesion layer 112, for example, a CrTi-based amorphous layer can be selected.

  The soft magnetic layer 114 is a layer that temporarily forms a magnetic path during recording in order to pass magnetic flux in a direction perpendicular to the recording layer in the perpendicular magnetic recording method. The soft magnetic layer 114 is provided with AFC (Antiferro-magnetic exchange coupling) by interposing a nonmagnetic spacer layer 114b between the first soft magnetic layer 114a and the second soft magnetic layer 114c. Can be configured. As a result, the magnetization direction of the soft magnetic layer 114 can be aligned along the magnetic path (magnetic circuit) with high accuracy, and the vertical component of the magnetization direction is extremely reduced, so that noise generated from the soft magnetic layer 114 is reduced. Can do. The compositions of the first soft magnetic layer 114a and the second soft magnetic layer 114c include a Co-based alloy such as CoTaZr, a Co-Fe based alloy such as CoCrFeB, and a Ni-Fe such as a [Ni-Fe / Sn] n multilayer structure. A system alloy or the like can be used.

  The pre-underlayer 116 is a non-magnetic alloy layer, and acts to protect the soft magnetic layer 114 and the easy magnetization axis of the hexagonal close packed structure (hcp structure) included in the underlayer 118 formed thereon is a disk. A function for aligning in the vertical direction is provided. The pre-underlayer 116 preferably has a (111) plane of a face-centered cubic structure (fcc structure) parallel to the main surface of the disk substrate 110. The material of the front ground layer can be selected from Ni, Cu, Pt, Pd, Zr, Hf, and Nb. Furthermore, it is good also as an alloy which contains these metals as a main component and contains any one or more additional elements of Ti, V, Ta, Cr, Mo, and W. For example, NiW, CuW, or CuCr can be suitably selected as the fcc structure.

  The underlayer 118 has an hcp structure, and has a function of growing a Co hcp crystal of the magnetic recording layer 122 as a granular structure. Therefore, the higher the crystal orientation of the underlayer 118, that is, the more the (0001) plane of the crystal of the underlayer 118 is parallel to the main surface of the disk substrate 110, the more the orientation of the magnetic recording layer 122 is improved. Can do. Ru is a typical material for the underlayer 118, but in addition, it can be selected from RuCr and RuCo. Since Ru has an hcp structure and the lattice spacing of crystals is close to Co, the magnetic recording layer 122 containing Co as a main component can be well oriented.

  When the underlayer 118 is made of Ru, a two-layer structure made of Ru can be obtained by changing the gas pressure during sputtering. Specifically, when forming the second base layer 118b on the upper layer side, the Ar gas pressure is set higher than when forming the first base layer 118a on the lower layer side. When the gas pressure is increased, the free movement distance (mean free path) of the Ru ions to be sputtered is shortened, so that the film formation rate is reduced and the crystal separation can be improved. Further, by increasing the pressure, the size of the crystal lattice is reduced. Since the size of the Ru crystal lattice is larger than that of the Co crystal lattice, if the Ru crystal lattice is made smaller, it approaches that of Co, and the crystal orientation of the Co granular layer can be further improved.

The nonmagnetic granular layer 120 is a nonmagnetic granular layer. A nonmagnetic granular layer is formed on the hcp crystal structure of the underlayer 118, and the granular layer of the first magnetic recording layer 122a is grown thereon, so that the magnetic granular layer can be grown from the initial growth stage (rise). Has the effect of separating. The composition of the nonmagnetic granular layer 120 can be a columnar granular structure by segregating nonmagnetic substances between nonmagnetic crystal grains made of a Co-based alloy to form grain boundaries. In particular, CoCr—SiO ₂ and CoCrRu—SiO ₂ can be suitably used, and Rh (rhodium), Pd (palladium), Ag (silver), Os (osmium), Ir (iridium), Au (instead of Ru) Gold) can also be used. A nonmagnetic substance is a substance that can form a grain boundary around magnetic grains so that exchange interaction between magnetic grains (magnetic grains) is suppressed or blocked, and is cobalt (Co). Any non-magnetic substance that does not dissolve in solution can be used. Examples thereof include silicon oxide (SiOx), chromium (Cr), chromium oxide (CrO ₂ ), titanium oxide (TiO ₂ ), zircon oxide (ZrO ₂ ), and tantalum oxide (Ta ₂ O ₅ ).

The magnetic recording layer 122 has a columnar granular structure in which a nonmagnetic substance is segregated around magnetic grains of a hard magnetic material selected from a Co-based alloy, an Fe-based alloy, and a Ni-based alloy to form a grain boundary. It is a magnetic layer. By providing the nonmagnetic granular layer 120, the magnetic grains can be continuously epitaxially grown from the granular structure. In the present embodiment, the first magnetic recording layer 122a and the second magnetic recording layer 122b having different compositions and film thicknesses are used. The first magnetic recording layer 122a and the second magnetic recording layer 122b are all non-magnetic materials such as oxides such as SiO ₂ , Cr ₂ O ₃ , TiO ₂ , B ₂ O ₃ , Fe ₂ O ₃ , BN, etc. Nitride and carbides such as B ₄ C ₃ can be preferably used.

  Since the perpendicular magnetic recording medium 100 according to the present embodiment is a bit pattern type, each recording bit is separated and independent. Therefore, the magnetic recording layer 122 does not necessarily have a granular structure. However, the SNR can be improved by the configuration in which the magnetic recording layer 122 has a granular structure. Furthermore, when the perpendicular magnetic recording medium 100 is a discrete track type, the SNR can be remarkably improved.

  In the present embodiment, the magnetic grains of the magnetic recording layer 122 are made of CoCrPt, but contain one or more elements selected from the group consisting of Fe, Pt, Ru, Co, Cr, and Pd (for example, , CoFeCrPt).

  The continuous layer 124 is a layer that is magnetically continuous in the in-plane direction on the magnetic recording layer 122 having a granular structure. By providing the continuous layer 124, in addition to the high density recording property and low noise property of the magnetic recording layer 122, it is possible to improve the reverse domain nucleation magnetic field Hn, improve the heat-resistant fluctuation characteristic, and improve the overwrite characteristic. In this embodiment, the continuous layer 124 is formed on the magnetic recording layer 122, but may be formed below. When the perpendicular magnetic recording medium 100 is a bit pattern type magnetic recording medium as in this embodiment, the continuous layer 124 is not necessarily provided.

  The protective layer 126 can be formed by depositing carbon by a CVD method while maintaining a vacuum. The protective layer 126 is a protective layer for protecting the perpendicular magnetic recording layer from the impact of the magnetic head. In general, carbon deposited by the CVD method has improved film hardness compared to that deposited by the sputtering method, so that the perpendicular magnetic recording layer can be protected more effectively against the impact from the magnetic head.

<Magnetic track pattern formation process>
Next, in the magnetic recording layer 122 of the present embodiment, a magnetic recording portion as a magnetically separated recording region and a non-recording portion that is provided between the magnetic recording portions and magnetically separates the magnetic recording portion are formed. The magnetic pattern forming process will be described in detail. Here, the magnetic pattern forming step may be performed immediately after the magnetic recording layer forming step, or may be performed after performing the continuous layer forming step and the protective layer forming step. For ease of understanding, the magnetic recording portion and the non-recording portion are collectively referred to as a magnetic region unless otherwise specified.

  In this embodiment, the magnetic pattern forming step is performed after the protective layer forming step. Accordingly, it is not necessary to form a protective layer after the magnetic pattern forming step, and the manufacturing process is simplified, thereby improving productivity and reducing contamination in the manufacturing process of the perpendicular magnetic recording medium 100. Can do.

  FIG. 2 is an explanatory diagram for explaining a magnetic pattern forming process according to the present embodiment. In FIG. 2, the description of the layer closer to the disk substrate 110 than the magnetic recording layer 122 is omitted for easy understanding. The magnetic pattern forming process includes a resist layer film forming process, a patterning process, an ion implantation process, and a removal process. Hereinafter, each process in the magnetic pattern forming process will be described.

<Resist layer formation process>
As shown in FIG. 2A, a resist layer 130 is formed on the protective layer 126 by using a spin coating method. As the resist layer 130, SOG (Spin On Glass) mainly composed of silica, a general novolac-type photoresist, or the like can be suitably used.

<Patterning process>
As shown in FIG. 2B, the magnetic pattern is transferred by impressing a stamper 132 against the resist layer 130 (imprint method). The stamper 132 has a concavo-convex pattern of magnetic regions corresponding to the patterns of the magnetic recording portion to be transferred and the non-recording portion. The stamper 132 can also have a concave / convex pattern in the servo area for storing servo information such as a preamble part, an address part, and a burst part, in addition to the concave / convex pattern in the magnetic area.

  After the magnetic pattern is transferred to the resist layer 130 by the stamper 132, the stamper 132 is removed from the resist layer 130, thereby forming an uneven pattern in the resist layer 130. In the present embodiment, a fluorine-based release agent is applied to the surface of the stamper 132. Thereby, the stamper 132 can be favorably peeled from the resist layer 130.

  In this embodiment, the patterning process uses an imprint method using the stamper 132, but a photolithography method can also be used suitably. However, when using the photolithography method, in the resist layer forming step, the photoresist is formed as a resist layer, and the formed photoresist is exposed and developed using a mask to form a magnetic track portion. The predetermined pattern is transferred.

<Ion implantation process>
As shown in FIG. 2C, ions are implanted into the magnetic recording layer 122 through the protective layer 126 from the recesses of the resist layer 130 patterned into a predetermined pattern in the patterning step. . This makes it possible to amorphize the crystal in the ion-implanted portion of the magnetic recording layer 122 into which ions have been implanted, and to magnetically isolate the portion under the convex portion of the resist layer 130. It becomes possible.

  In particular, in this embodiment, ion implantation is performed as follows. That is, the layer to which ions are implanted is determined by adjusting the amount of energy for implanting ions, and the total amount (dose amount) of ions implanted into each layer is determined by adjusting the time for maintaining the amount of energy.

  Therefore, in the region 134 (the region to be a non-recording portion indicated by hatching in FIG. 2) under the concave portion of the resist layer 130, only a portion belonging to the magnetic recording layer 122 can be ion-implanted and continuous. It is also possible to perform ion implantation using only the portion belonging to the layer 124 as a target.

  According to the above configuration, by increasing / decreasing the amount of energy, ions can be implanted into the continuous layer 124 regardless of whether the continuous layer 124 is formed above or below the magnetic recording layer 122. Thereby, the coercive force Hc adjusted mainly by the magnetic recording layer 122 and the reverse domain nucleation magnetic field Hn mainly adjusted by the continuous layer 124 can be individually adjusted. As a result, it is possible to improve the write characteristics and read characteristics to the magnetic recording portion while maintaining a good SNR.

In this embodiment, one or more of Ar, N ₂ , and O ₂ are used as ions to be implanted, but B, P, Si, F, C, In, Bi, Kr, Ar, Xe, W, As, One or more ions selected from the group consisting of Ge, Mo, Sn, N ₂ , and O ₂ may be implanted.

  The amount of energy for implanting ions is 1 to 50 keV. If the amount of energy for implanting ions is less than 1 keV, magnetic separation of the magnetic recording portion in the magnetic recording layer 122 is not performed properly, causing noise when reading by the head. If it is 50 keV or more, demagnetization or amorphization of the magnetic recording layer 122 is promoted too much, the read / write characteristics are deteriorated, or a portion that becomes a magnetic recording portion under the convex portion of the resist layer 130 Until it is demagnetized.

Furthermore, the total amount (dose amount) of ions to be implanted is 1E15 to 1E17 atoms / cm ² . Thereby, it is possible to improve the read / write characteristics of the magnetic recording portion while maintaining a good SNR.

  In the case of forming a concavo-convex pattern in the servo area for storing servo information, the relative permeability of the area separating at least the preamble part, the address part, the burst part, etc. in the servo area of the magnetic recording layer 122 is set to 2 To 100. As a result, it is possible to increase the servo information read characteristic (output).

<Removal process>
As shown in FIG. 2D, the resist layer 130 is removed by RIE (Reactive Ion Etching) using a fluorine-based gas. In the present embodiment, SF ₆ is used as an etching gas, but the present invention is not limited to this, and any one or a plurality of mixed gases selected from the group consisting of CF ₄ , CHF ₃ , and C ₂ F ₆ are also suitable. Can be used.

  In this embodiment, since SOG is used as the resist layer 130, etching is performed using a fluorine-based gas. However, it goes without saying that the type of gas is appropriately changed depending on the material of the resist layer 130. For example, when a novolac photoresist is used as the resist layer 130, RIE using oxygen gas is suitable.

  In this embodiment, the RIE plasma source uses ICP (Inductively Coupled Plasma) capable of generating high-density plasma at a low pressure. However, the present invention is not limited to this, and ECR (Electron Cyclotron Resonance) plasma, A parallel plate RIE apparatus can also be used.

(Lubrication layer forming process)
The lubricating layer 128 can be formed of PFPE (perfluoropolyether) by dip coating. PFPE has a long chain molecular structure and binds with high affinity to N atoms on the surface of the protective layer 126. Due to the action of the lubricating layer 128, even if the magnetic head comes into contact with the surface of the perpendicular magnetic recording medium 100, damage or loss of the protective layer 126 can be prevented.

(Examples and evaluation)
On the disk substrate 110, a film was formed in order from the adhesion layer 112 to the continuous layer 124 in an Ar atmosphere by a DC magnetron sputtering method using a film forming apparatus that was evacuated. The adhesion layer 112 was made of CrTi. In the soft magnetic layer 114, the composition of the first soft magnetic layer 114a and the second soft magnetic layer 114c was CoCrFeB, and the composition of the spacer layer 114b was Ru. The composition of the pre-underlayer 116 was a NiW alloy having an fcc structure. For the underlayer 118, the first underlayer 118a was formed with Ru under high-pressure Ar, and the second underlayer 118b was formed with Ru under low-pressure Ar. The composition of the nonmagnetic granular layer 120 was nonmagnetic CoCr—SiO ₂ . The magnetic recording layer 122 was made of CoCrPt containing at least Pt. The composition of the continuous layer 124 was CoCrPtB. The protective layer 126 was formed using C ₂ H ₄ and CN by a CVD method.

  Thereafter, SOG mainly composed of silica was formed as a resist layer 130 on the surface of the protective layer 126 by spin coating. Further, the magnetic pattern was transferred by pressing the stamper 132 against the resist layer 130 by imprinting. The stamper 132 has a magnetic area for recording / reproduction including a magnetic recording section as a recording area to be transferred and a non-recording section provided between the magnetic recording sections, a preamble section, an address section, and a burst. And a servo area for storing servo information such as a portion, and a concavo-convex pattern corresponding to each pattern.

  After the magnetic pattern was transferred to the resist layer 130 by the stamper 132, the uneven pattern was transferred to the resist layer 130 by removing the stamper 132 from the resist layer 130.

Further, ions were implanted from the recesses of the resist layer 130 patterned into a predetermined pattern into the magnetic recording layer 122 through the protective layer 126 using the ion beam method. At this time, ion implantation was performed with N ₂ ions as an ion to be implanted, an energy amount of about 20 keV, and a dose amount of 2E16 atoms / cm ² .

  The lubricating layer 128 was formed using PFPE by a dip coating method.

  FIG. 3 is a diagram illustrating conditions for ion implantation performed in the embodiment of the present invention. FIG. 3A is a graph showing the change in the amount of energy during ion implantation along the time axis. FIGS. 3B and 3C are diagrams schematically showing the ion concentration distribution in the magnetic recording layer 122 obtained by this example and the comparative example.

  In this embodiment, the energy amount for implanting ions was changed stepwise, and the time for holding each energy amount was changed. For example, as shown by a solid line in FIG. 3A, ion implantation is performed for 15 seconds in total of 13 keV for 5 seconds, 10 keV for 5 seconds, and 7 keV for 5 seconds.

  Thus, by changing the energy amount of ion implantation stepwise, the arrival depth of ion implantation changes stepwise. In the case of this example, the first magnetic recording layer 122a (13 keV for 5 seconds), the second magnetic recording layer 122b (10 keV for 5 seconds), and the continuous layer 124 (7 keV for 5 seconds) in order of depth. Ion implantation is performed on the target.

  In this way, not only the second magnetic recording layer 122b located at the center of the magnetic recording layer 122 but also the first magnetic recording layer 122a and the continuous layer are each given an equal dose amount (energy retention time). This is because it is possible to ensure magnetic separation.

  However, all of the first and second magnetic recording layers 122a, 122b and the continuous layer 124 may be non-recording portions 134 having a relative magnetic permeability of 2 to 100 or less (referred to as semi-hard), and are completely non-magnetic. do not have to.

  In this embodiment, the ion implantation energy amount is changed only in three stages, but it may be changed in any number of stages.

  As shown in FIG. 3B, in this embodiment, the ion concentration is a continuous layer≈first magnetic recording layer≈second magnetic recording layer, similar to the energy holding time. On the other hand, as shown by a broken line in FIG. 3A, in the comparative example, implantation is performed for 15 seconds with an ion implantation energy of 10 keV. Compared with the comparative example shown in FIGS. 3A and 3C, this example has an appropriate concentration distribution according to the layer into which ions are implanted, and has a coercive force Hc and a reverse domain nucleation magnetic field Hn. Can be adjusted individually to maintain the good SNR and improve the write characteristics and read characteristics to the magnetic recording portion.

  In this embodiment, the ion implantation energy is first increased and gradually decreased, and ions are sequentially implanted from the deep layer to the gradually shallower layer (continuous layer 124 → second magnetic recording layer 122b → first magnetic recording layer 122a). However, ion implantation may be performed in the reverse order.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above-described embodiment, ion implantation is performed on the resist layer 130 to which the concavo-convex pattern has been transferred without performing a separate process. However, the present invention is not limited to this, and the resist layer 130 to which the concavo-convex pattern has been transferred remains on the bottom surface of the recess. After the resist layer to be removed is removed by etching or the like, ion implantation may be performed.

  In the above embodiment, the present invention is not limited to this by ion implantation. By etching the resist layer 130 to which the concavo-convex pattern has been transferred, the magnetic recording layer is formed with a convex portion and a concave portion based on a predetermined pattern. Alternatively, the concave portion of the magnetic recording layer may be configured.

  Furthermore, in the above-described embodiment, the bit pattern type magnetic recording medium has been described. However, the present invention is not limited to this. As a discrete track medium in which magnetic recording portions and non-recording portions formed in a linear shape are alternately arranged in the radial direction. Also good. Thereby, it is possible to improve the thermal fluctuation resistance of the magnetic recording medium and to promote higher recording density.

  In the above embodiment, the magnetic recording layer is composed of two layers having a granular structure. However, the present invention is not limited to this, and the magnetic recording layer may be composed of one layer or a plurality of layers, and may not have a granular structure. Good.

  Furthermore, in the above-described embodiment, the perpendicular magnetic recording medium has been described as the magnetic recording medium. However, it can also be suitably used for an in-plane magnetic recording medium.

  The present invention can be used as a method of manufacturing a magnetic recording medium mounted on a magnetic recording type HDD or the like and as a magnetic recording medium.

DESCRIPTION OF SYMBOLS 100 ... Perpendicular magnetic recording medium 110 ... Disk base | substrate 112 ... Adhesion layer 114 ... Soft magnetic layer 114a ... First soft magnetic layer 114b ... Spacer layer 114c ... Second soft magnetic layer 116 ... Pre-underlayer 118 ... Underlayer 118a ... First Underlayer 118b ... Second underlayer 120 ... Nonmagnetic granular layer 122 ... Magnetic recording layer 122a ... First magnetic recording layer 122b ... Second magnetic recording layer 124 ... Continuous layer 126 ... Protective layer 128 ... Lubricating layer 130 ... Resist layer 132 ... Stamper 134 ... Area under the recess after the ion implantation process (area to be a non-recording area)

Claims (12)

A magnetic recording layer forming step of forming a magnetic recording layer on the substrate;
A resist layer forming step of forming a resist layer on the magnetic recording layer;
A patterning step of partially changing the thickness of the resist layer by processing the resist layer to form a predetermined pattern having recesses and protrusions;
An ion implantation step of implanting ions into a plurality of layers including the magnetic recording layer with the resist layer interposed therebetween;
Including
In the ion implantation step, a layer to which ions are implanted is determined by adjusting an energy amount for implanting ions, and a total amount of ions to be implanted into each layer is determined by adjusting a time for holding the energy amount. A method for manufacturing a magnetic recording medium. Before the resist layer forming step,
A continuous layer film forming step of forming a continuous layer composed of a thin film that is magnetically continuous in the plane direction adjacent to the upper or lower side of the magnetic recording layer,
2. The magnetic recording medium according to claim 1, wherein in the ion implantation step, ions are implanted also into the continuous layer by adjusting an energy amount for implanting the ions and a time for retaining the energy amount. Production method. In the ion implantation step, 1 selected from the group consisting of B, P, Si, F, C, In, Bi, Kr, Ar, Xe, W, As, Ge, Mo, Sn, N ₂ and O ₂ or The method for manufacturing a magnetic recording medium according to claim 1, wherein a plurality of ions are implanted.   3. The method of manufacturing a magnetic recording medium according to claim 1, wherein, in the ion implantation step, an energy amount for implanting ions is 1 to 50 keV. 3. The magnetic recording medium according to claim 1, wherein in the ion implantation step, a total amount of the implanted ions is 1.0 × 10 ^{15 to} 1.0 × 10 ¹⁷ atoms / cm ^2. Manufacturing method.   The magnetic recording medium according to claim 1 or 2, wherein the magnetic recording layer contains one or more elements selected from the group consisting of Fe, Pt, Ru, Co, Cr, and Pd. Method.   3. The magnetic recording medium according to claim 1, wherein the magnetic recording layer is a ferromagnetic layer having a granular structure in which a grain boundary portion made of a nonmagnetic substance is formed between crystal grains grown in a columnar shape. Manufacturing method. When ions are implanted in the ion implantation step, the magnetic recording layer is divided into a magnetic recording portion as a recording region under the convex portion of the resist layer and a non-recording portion under the concave portion of the resist layer. Become
The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic recording medium is a bit patterned medium in which the magnetic recording portions are scattered on a main surface. When ions are implanted in the ion implantation step, the magnetic recording layer is divided into a magnetic recording portion as a recording region under the convex portion of the resist layer and a non-recording portion under the concave portion of the resist layer. Become
3. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is a discrete track medium in which the magnetic recording portions and the non-recording portions formed in a linear shape are alternately arranged in a radial direction. Manufacturing method.   2. The ion implantation is performed by sequentially implanting ions from a deep layer to a shallow layer by adjusting an energy amount for ion implantation so as to gradually decrease from a high value to a low value. 3. A method for producing a magnetic recording medium according to 2.   2. The ion implantation is performed in such a manner that the amount of energy for implanting ions is adjusted so as to gradually increase from a low value to a high value, and ions are implanted in order from a shallow layer to a deeper layer. 3. A method for producing a magnetic recording medium according to 2.   A magnetic recording medium manufactured using the method for manufacturing a magnetic recording medium according to claim 1.

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